Documentation update

[danipavic]

The following list represents parts of the libs with missing or inadequate documentation. The documentation should be added or extended.

1. findOne function on the ModelService also support customUrl which is not documented. The library consumer should be able to see all available parameters when reading the documentation.
2. Add Pagination class example. The documentation briefly glances over what the class is, but it is not immediately clear what has to be done without diving into the library types. Example should be added similar to other classes/services and the actual documentation should be longer than one sentence.
3. Update Getting Started section to reflect more modern Angular apps. Best case scenario, both AppModule and AppConfig approaches should be documented, however I think it is unlikely that any old Angular applications will start using the library so the documentation can only document the AppConfig standalone approach.